Field of the Invention
The present invention relates to a double pipe heat exchanger and a method of manufacturing the same, and more particularly, to a double pipe heat exchanger and a method of manufacturing the same that enables a heat exchange between a fluid flowing in an outer pipe and a fluid flowing in an inner pipe by disposing the inner pipe having a spiral structure at the outer pipe.
Description Of The Related Art
A heat exchange between a low temperature and a high temperature is required in various fields, and an apparatus such as a heat exchanger may be used for a heat exchange between a high temperature fluid and a low temperature fluid. For example, in a refrigerator or a vehicle, for a heat exchange, a double pipe structure is used that enables a high temperature fluid and a low temperature fluid to exchange a heat while simultaneously flowing. For example, by adding a fluid line between a condenser and an evaporator to a suction line between an evaporator and a compressor, a double pipe may be formed. Thereby, a low temperature fluid of the suction line may absorb a high temperature heat of the fluid line. Therefore, cooling efficiency of a cooling apparatus may be improved. A structure of a double pipe heat exchanger of various forms is well-known in this field.
A conventional double pipe heat exchanger has an inner pipe 10 and an outer pipe 20, as illustrated in FIG. 1. The inner pipe 10 has a first flow channel 12 therein, and in the first flow channel 12, a first fluid is injected and flows.
The outer pipe 20 is installed at a circumference of an outer surface of the inner pipe 10. Particularly, a second flow channel 30 is formed between the outer pipe 20 and the inner pipe 10, and in the second flow channel 30, a second fluid is injected and flows. In this case, at an outer circumferential surface of the inner pipe 10, a helical groove 14 is formed, and a second fluid flows along the helical groove 14.
Therefore, a second fluid injected into the second flow channel 30 flows at a temperature different from the first fluid flowing along the first flow channel 12; thus, a mutual heat exchange operation occurs.
In a conventional double pipe heat exchanger produced in such a structure, by the helical groove 14 formed at an outer circumferential surface of the inner pipe 10, a portion protruded between the helical grooves 14 contacts an inner circumferential surface of the outer pipe 20; thus, a flow rate is not partially secured and a heat exchange area between the first fluid and the second fluid is thereby reduced so that heat exchange efficiency may deteriorate.
Further, in the process of coupling the inner pipe 10 to the outer pipe 20, it is preferable that both side ends of the helical groove 14 formed at the inner pipe 10, i.e., a portion in which the helical groove 14 starts and terminates, are coupled to correspond to a portion in which an external fluid of the outer pipe 20 is injected and discharged; however, in a state in which the inner pipe 10 is inserted into the outer pipe 20, a movement occurs at the inner pipe 10 inserted into the outer pipe 20 when an additional process is performed. As a result, there is a problem that the inner pipe 10 cannot be coupled at an accurate location.
A further problem is that, when coupling the inner pipe 10 to the outer pipe 20 by a welding process, it is difficult to weld so that sufficient airtightness is maintained in a portion coupling the inner pipe 10 to the outer pipe 20.